This disclosure relates to devices and methods typically used for simultaneously bursting or destroying buried pipes and pulling a replacement pipe though the same location as the destroyed pipe. Such methods of pipe replacement are sometimes referred to as “trenchless pipe replacement systems” and require only two pits to be dug, one at each end of the pipe to be replaced. One end of a pulling cable is attached to the front end of a bursting pipe head device, and the other end is threaded through the existing pipe from an entry point accessible in the entry pit and provided to a pulling apparatus located in the exit pit. The pulling apparatus then pulls the cable and the attached bursting pipe head device through the existing cable, typically by a hydraulic mechanism. The bursting pipe head device bursts or fractures the existing pipe as it is pulled through, and brings with it replacement or product pipe attached at the back end of the bursting pipe head device.
There is an on-going desire to minimize the size of the pits to be dug; increase the facility and ease for (1) introducing replacement pipe into the existing pipe location, (2) pulling the replacement pipe through the existing pipe; and (3) disengaging the cable and removing the bursting pipe head device from the replacement pipe once it is in place; as well as increasing the facility and ease of maintaining and using a bursting pipe head device.
Bursting head devices and methods of use are well-known and characterized in the art. Typically, these devices include (1) a pipe bursting head typically having a tapered nose or leading portion and structured to break apart the existing pipe as the bursting head is pulled through the existing buried pipe, (2) a cable connection that allows cable to pull the pipe breaking head through the existing buried pipe, and (3) a means for connecting new replacement pipe to the back end of the bursting head so that the cable pulls the new pipe into and through the existing buried pipe as it is burst by the bursting head. Typically, a hydraulic pulling device pulls the cable and the attached bursting head and replacement pipe through existing buried burst pipe.
The bursting pipe head devices of the art typically have a static, non-flexible means for connecting the new pipe to the back end of the bursting head device. This inability to allow movement, rotation or flexing at the connection point makes entry of the new pipe into the existing pipe at the starting point or entry pit difficult, often requiring the need to dig a larger pit than desired, so as to reduce the angle of entry of the new pipe into the buried pipe.
In addition, existing bursting pipe head devices of the art typically use a pin and clevis type arrangement external to and extending from the front end of the device to attach cable to the bursting head, typically by means of a swaged connection. Alternatively, the cable is attached to the bursting head by means of an internal clamping mechanism. The external cable attachment devices are limited in utility in that external attachment adds to the overall length of the device, thereby limiting the distance the bursting head device can be pulled into the exit or pulling pit from the buried pipe terminus with pulling devices of the art. This can require the need to dig the bursting head device out of the earth. The internal clamping mechanisms of the art also can be difficult and problematic from which to disengage the cable easily once the replacement pipe is in place. Moreover, where the cable connection is by means of an internal clamping mechanism, ready access to the internal clamping mechanism and/or ease of cable release is lacking in the pipe bursting head devices of the art.
US Patent Application Publications 2002/0081154 A1, US 2008/0181728, and US 2012/0321391 A1, and U.S. Pat. Nos. 6,357,967 B1 and 6,913,091 B2 are representative of the state of pipe bursting head devices and methods of use in the art.
The present disclosure describes improvements in the bursting head device and method of use that overcomes deficiencies in the bursting pipe head devices and methods of the prior art.